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Plz HELP! When AC on, does your compressor make a whirring sound when you accelerate?

freefallin

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This is the 3rd compressor im replacing this week!

When the AC is on and i accelerate, the compressor makes a whirring/whining sound! On park, if i lightly step on the gas to 1000-1500rpm, the compressor makes a sound similar to the steering wheel/pump whir you hear when the fluid is low. And between 3000-3500rpm, it makes a more pronounced whirring sound like rrrrrrrr mixed with the steering type sound! You cant hear them if the radio is on or the windows are open but clear otherwise!

Changed 2 compressors that i bought used but under warranty cz i thought/think the compressor was defective! On the 3rd one now and noticing the same noise.

Is this normal or are the compressors bad?

Car: VY ECOTEC
 

Nut Kracker

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I couldn't see that all the compressors are bad.
How is the belt. It could be worn or you are not tensioning it up tight enough and it's slipping. The belt has to be fairly tight because the pump is harder for the
engine to turn unlike the alternator that is fairly easy.
 

Darren_L

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It's very unlikely that you'd have 3 faulty compressors.

I'd be checking for voltage drop in the compressor wire circuit
Those compressor clutches draw quite a bit of current. If there is a bad earth and/or other resistance in connections etc then it's entirely possible that the compressor clutch isn't getting full current and slipping as a result.
 

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It's very unlikely that you'd have 3 faulty compressors.

I'd be checking for voltage drop in the compressor wire circuit
Those compressor clutches draw quite a bit of current. If there is a bad earth and/or other resistance in connections etc then it's entirely possible that the compressor clutch isn't getting full current and slipping as a result.

Good point. Check the a/c relay. It could have a bad internal/extenal connection causing resistance in the circuit.
 

freefallin

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Thanks for your contribution guys!!

I couldn't see that all the compressors are bad.

Exactly what i thought at first... but then i figured i might be having a really bad run of luck! Then i thought maybe the recovered r134 was bad and damaging the compressor.

How is the belt. It could be worn or you are not tensioning it up tight enough and it's slipping. The belt has to be fairly tight because the pump is harder for the
engine to turn unlike the alternator that is fairly easy.

if that was the case then wouldnt it be making noise regardless of whether the AC was on or not? Or is it a different story when AC is on? If so, i fail to see the significance of the stress involved to turn the clutch since it could pretty easily be turned by hand, not much effort needed! Unless the resistance increase when the clutch/pump is turning at higher speed! Im just applying logic here...dont really know the technicalities of how compressors work. Feel free to enlighten me!
I changed the belt about a month ago so its fairly new! The tension is another story...not really sure there. But ill tell you this; there is hardly any effort needed in removing or putting it back on! Once i relax the tensioner, i could slip the belt off with one finger. So idk if that indicates the tension level and if it is at the right tension or not.
 

freefallin

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It's very unlikely that you'd have 3 faulty compressors.

I'd be checking for voltage drop in the compressor wire circuit
Those compressor clutches draw quite a bit of current. If there is a bad earth and/or other resistance in connections etc then it's entirely possible that the compressor clutch isn't getting full current and slipping as a result.

Interesting point!

All i know is that my alternator reads 13.65 (engine fans on high speed), 13.68 (engine fans on normal speed) when AC is on. 13.71 AC off! IDK if thats good or normal!

As for resistance and all what you said, i would appreciate it very much if you could tell me how exactly to check.
 

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Thanks for your contribution guys!!



Exactly what i thought at first... but then i figured i might be having a really bad run of luck! Then i thought maybe the recovered r134 was bad and damaging the compressor.



if that was the case then wouldnt it be making noise regardless of whether the ac was on or not? Or is it a different story when as is on? If so, i fail to see the significance of the stress involved to turn the clutch since it could pretty easily be turned by hand, not much effort needed! Unless the resistance increase when the clutch/pump is turning at higher speed! Im just applying logic here...dont really know the technicalities of how compressors work. Feel free to enlighten me!
I changed the belt about a month ago so its fairly new! The tension is another story...not really sure there. But ill tell you this; there is hardly any effort putting removing the belt or putting it back on! Once a relax the tensioner, i could slip the belt off with one finger! So idk if that indicates the tension level and if it is at the right tension or not.

It wouldn't necessarily make a noise when the A/C is off as for reasons below.
There is a ton more pressure on the compressor when you turn it on. That's why the tension on the belt is very important. Have a look at the underside of the belt. If it's shiny, it's slipping.
When it's off you can just about spin the pulley with a feather. But when its on, it operates a bunch of little pistons, maybe 5 or 6 that "compress" the refridgerant gas. Having the A/C on can reduce your cars power by around 7 kilowatts or more therefore reducing fuel economy. As a matter of fact, when I had my 4x4, I read about a guy who converted an A/C compressor into an "air" compressor for his 4X4 so he could pump up his tyres. They do put a lot of strain on the engine.
When it's turned on, the computer (ECU/PCM) delays the start of the A/C by a couple of seconds so as to up the idle of the engine so it maintains the correct idle speed. If it didn't do this, the idle would be reduced dramatically and possibly stall the engine. If the engine goes to W.O.T. (Wide open throttle) The computer shuts off the compressor so as not to over rev it. It then will switch back on when the revs return to a point that will allow it to operate. Thats how much of a strain the A/C compressor takes out of the engine.
So once again......Make sure the belt is tight. But don't over do it because it can damage the bearings not only in the compressor, but in the alternator, water pump and power steering as well. If you are not sure, take it to a mechanic.
Hope this helps.
 

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Interesting point!

All i know is that my alternator reads 13.65 (engine fans on high speed), 13.68 (engine fans on normal speed) when AC is on. 13.71 AC off! IDK if thats good or normal!

As for resistance and all what you said, i would appreciate it very much if you could tell me how exactly to check.

Hmmmmm......Should be higher around 14.something. Could be due to belt slipage or the alternator is faulty and not putting out enough current to power the A/C
Find the A/C relay. Not sure on your car where it is. Probably under the bonnet in the fuse box. Pull it out. there will be 4 pins on it. Check to see if they are clean.
Pull out the headlight relay and try that on the A/C. They should be the same......40 amp.
 

freefallin

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Thanks for the info nut cracker (nice screen name btw)!

I checked a few mins ago! Its not shiny and looks good. Little confused about how to determine the correct/appropriate tension though!

Mechanics here are retards! If you take your car here for anything, they will either tell you to replace the part or that its ok! Fixing is something that is not part of their job description...replacing, yeah...but not fixing!
Even determining whether something is good or not is a pain! Most of the time they will tell you to replace something when there is nothing wrong with it or when the problem is something else! Went to a shop a few weeks ago to check my AC system...after paying the checkup fee, they told me that i need to replace the compressor, ac lines and evaporator! I was like what the! Even the evaporator?! I asked them repeatedly if they were sure i had to replace it! They said yes and that they were all leaking. Basically the only thing left was the condensor! I bought a new evaporator and spent 4 days opening up the dashboard only to find my evaporator was good as new! So... money and time spent cz of an incompetent mechanic. And the shop is supposed to be the best in town! Everyone knew it and recommended it!

At the end, it turned out i had a leak only in the compressor and the valve looking thing on the fireframe(?); basically a $1 o-ring and 5 mins to replace it.
So yeah, i try to avoid mechanics now, rather get info here and do it myself!
 

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I have a whirring noise also on my VZ SV6 when my air con is on, more so if its up high.

It works flawlessly but the noise it makes reminds me of a supercharger, weirdly enough my car goes BETTER with the air con on.. which i still cannot understand why.

I always put the noise down as 'normal', but i guess that may not be the case...
 
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